Project Summary Our research project will be a collaborative effort supported by all of the MobileToolbox Cores. The project will function as the vehicle within which we develop and psychometrically evaluate our cognitive assessment tools. We will do this by accomplishing the following specific aims. Aim 1: We will develop a repository of public-domain cognitive ability measures that enhance the assessment of cognitive change across the lifespan by enabling self-administered testing via iOS and Android smartphones. The MobileToolbox measures will be designed around the technical specifications of a flexible and open software platform that enables external researchers to customize use of the mobile app to fit the needs of their studies. Researchers will be able to choose from a diverse selection of cognitive measures, including several cognitive tasks highly sensitive to change, along with measures of contextual variables of relevance to cognitive functioning (e.g., mood, personality, health status). Aim 2: Evaluate the psychometric properties of MobileToolbox instruments through implemention of a series of data collection protocols aimed at calibration, norming, and face-to-face validation against existing gold standards. We will calibrate Item Response Theory based measures by administering them to a large (N=4,800) general population calibration sample. All newly developed MobileToolbox measures will be validated against existing gold standards in a sample of healthy adults ages 20-85. The validation protocol will include face-to-face administration of the NIH Toolbox Cognition Battery, core sub-tests of the Wechsler Adult Intelligence Scale (WAIS-IV), and additional tests as needed. During this cross-sectional validation session, respondents (N=260) will complete the self-administered MobileToolbox via smartphone in an un-proctored setting. Additional validation will be undertaken in existing clinical (e.g., cognitively impaired, Parkinson?s disease) and general population (e.g. Healthy Aging Study, N=100,000) samples. Finally, we will identify normative values for the MobileToolbox measures using a large, nationally-representative sample (N=6,800). Sub-samples of respondents will be used to identify normative cognitive change by completing 3-, 12- and 24- month follow-up assessments.